drewfio

I've been working on an old Specialized Rockhopper, now getting to installing cranks. The cranks are New Albion XDT triple cranks. I popped them on by hand without tightening, and they look awfully close to the bottom bracket and frame. I'm concerned that the cranks will bottom out. Also worried there might not be clearance for the crank arm from the chainstay once installed. There only at most a few mm before reaching the end of the taper, where it looks like there is also some sort of stop or seal. Is this typical? Will these install correctly? Would getting a wider bottom bracket be preferable?

The manufacturer specifies a 113mm spindle for 47.5mm, which from reading Sheldon Brown (and other places) is correct chainline for mtb triple. So that is what I got—a Shimano BB UN300 73x113. I'm not sure these cranks are meant for a mountain bike however, since they are listed as touring cranks. Could this be contributing to the issue?

Thanks!

The_Joe

I'll ask the simple question first. Are you sure the BB is installed the right way round?

jdawginsc 

Dang. No room for error there. Those bb-300s are sort of different than the previous iterations that worked really well. The collar bothers me.

The old cartridge BB-series were much more easy to predict.

tombc

If OP was able to put in a bottom bracket backwards against the threads on both sides I doubt they'd need us at this point.

e: to be actually helpful - try it. install the chainrings and order a crank puller if you haven't yet. If it bonks anything, you need a longer spindle. Different bikes have different chain stays and so on, usually the spec sheet steers you right but you cannot be totally sure without trying.

squirtdad

I would put the rings on and see if you have clearance. you could use a spacer also to move BB out a bit

The_Joe

Good point. You know, I almost said "stupid question" instead of "simple question". Really got ahead of myself there.

bboy314

From the pics it seems fine. Throw the chainrings on, mount it and see how it fits.

If you do have to replace the BB, I’d go with something better than the UN300. They tend to wear out pretty fast because of the tiny bearings.

drewfio

Thanks for the reply

I have a crank puller. I've installed a few dozen square taper cranks in the past. Never had one sit so close to the bottom bracket before even tightening. I double checked other current bikes and none are that close on the taper even after installing. But those cranks are all, like the bikes and bottom brackets, older. So perhaps things have changed with new cranks and bottom brackets. Or maybe this is just wrong.

So you don't think there is any risk of damaging the cranks by just installing?

drewfio

So you think this is a typical/acceptable room on the taper before tightening the crank bolts at all? If so, it means the cranks would not move very far during installation. I don't think I've paid attention in the past to how much closer they go when installing the past since it never seemed worrisome.

drewfio

Fair question. I've made plenty of boneheaded mistakes in the past. But I'm pretty sure the bottom bracket is installed the right way around. The threading would not allow this (without very significant damage I suppose). There are L and R markings on the BB, and directional arrow on the NDS cup. And the spindle itself does not seem to be reversible/detachable like a cup and cone BB.

rgvg

Looks suspiciously like a Sugino XD2. Maybe OEM is Sugino? I do have an XD2 on a 113 spindle, but not on a mountain bike. Works fine.

Lamont Cobb

I love triple cranks. Being on my first resto job (Panasonic Tourist), I'm amazed at all the different standards for bicycle parts. My research on the Internet tells me that it's not getting better; if anything, it's getting worse.

unworthy1

hard to be certain with the angle of the shot but I'd say this spindle is too short (at least on the DS): I think the granny and/or middle ring might hit the chainstay, but you should do a "dry fitting" and see for certain. No reason to rely on anybody's guesswork based on one photo!
When you do get it all-on take a ruler and measure from the C/L of the seat tube to the C/L of the middle ring, should be about 47.5 to 50mm (per St. Sheldon, peace be upon him )

drewfio

I was actually planning on putting a 1x ring on, so that is why the other rings are not on. I have a few sizes of 1x rings—34, 36, 40—I was planning on test fitting. The But putting the granny on, if that hits the chainstays, that will tell me it is too short of a spindle, at least for this frame, so I will try that.

Chainring clearance and chainline aside, my primary concern was if installing the cranks on what looks to be a super tiny amount of remaining taper would bottom out and/or damage the crank.

drewfio

It's a New Albion branded, model XDT crank. From what I gather though, this is actually using Sugino molds. It is the same as to the Clipper Cranks that Rivendell sells. It actually has a Sugino crown logo stamped into the backside. So I think it is in fact the same spec as an XD.

My thought was that this was not meant for a mountain bike, and perhaps there is an issue with the difference between a 68x113 and a 73x113.

79pmooney

I'd put the rings on, mount it and start tightening. Stop and look often. Watch for that collar hitting the BB shell. Won't do much harm if it does except make the bike unridable. And scuff the collar where no one will see it. Watch for any of the chainring teeth hitting - paint. Watch for crank hitting - paint. If all those clear and you are up to torque - ride it! (Unless the teeth and crankset are within 2 mm or so and you are strong. More if the bike frame is flexy.)

If the crank is close, watch the other side too.

unworthy1

That's a factor of the "taper" not so much the spindle length (even tho it's also important) and don't see a pic that describes how much distance there is from the end of your DS spindle to the outboard edge of the square hole in this crank. And we don't need a pic just get it dry fitted and place a small metric ruler in the hole so it touches the flat end of the spindle and read to the edge of that hole...you should have at least 2 and mo'better is 3-4mm. if you don't install and torque down the DS crankbolt it should all pull apart easily enough.

This has only happened once in my many builds but I had a re-threaded BB shell (Brit shell with Ital threading so "Frankenbike" material) and everything else was "within spec" Good chain line, spindle taper and length but the Shimano 600 crank arm center casting came too close to the BB cup for my comfort.
So I took it to the bench grinder and removed some material off the backside!
Did not affect the fit but did create some clearance that wouldn't have been there otherwise.

zukahn1 

To make things work just add a 2mm drive side washer then adjust the shifters rest to work. I have done s bunch Shimano stuff this way seems to work just fine if the frame is good

madpogue 

Looks to me like the arm would hit the chainstay, or at least come to within a couple coats of paint distance.

'02 nrs

your crankarm end appears too close to the chainstay no? think the older un BB's were longer on the drive side.the new style are equal lengths.the next 73mm un300 available is a 118 x 73. you maybe able to install a 2mm spacer on the DS to get by though as mentioned.if you still have the old BB measure the spindle length from the DS lip & compare to the UN300.

drewfio

Okay, got the cranks mounted. The base of the crank reaches into the cup, but it seemed to install okay, and seems pretty solidly on there. The arm and 36t chainring clear the chainstays with sufficient room I believe. So I'm going to call this a success for now. Next step is to hook up shifting, and then it should be ready for a test ride. This is is intended to be a commuter for my wife.